I’ve recently purchased a Guardian 13kw standby generator with a transfer switch and load center panel. I have a couple of questions 1. The transfer panel had a total of 205 amps through 12 various breakers in it, can I replace some of them as long as I don’t go over the original 205 amps and use the correct size wire for each breaker. Example: could I replace a 40-amp 2-pole breaker with 2 20-amp single pole breakers? 2. Can I install a GFCI breaker in the transfer panel if I were to run a neutral wire to it from the main utility panel as long as it’s replacing the same size breaker? 3. I also have a 20 amp single pole breaker in my main panel with 2 leads going to it red and black and share the same neutral for switched outlets in the living room. Can I move just one of them and leave one where it is at without having a problem with the neutral. I know this is a lot but I hope you can help.
Thanks in advance for your time.
Dale Wagner

You do not add up the ratings of circuit breakers to match the rating of a panel, or any distribution equipment. The 200 amp load can be for one circuit or can be accumulated of several circuits. Install all the branch breakers you like in any combination, just be sure the total connected load does not exceed 200 amps.

Since the neutral from the generator must connect to the main system neutral in the main panel, the GFI breaker can have it's pigtail go back to the main neutral bar using the same size wire for the rating of the breaker.

Spliting the two wires on one breaker can be a problem. You will need to be absolutely sure the wire you move is on the same phase as the other one. If you don't, the current in the neutral can be doubled and overheat the wire. This can be difficult to understand and explain. Better you don't split this up unless you are sure of what you are doing.

tkrussell,

I know what you are talking about with the wire moving, but the way you said it is slightly ambiguous. To be clear:

If two hot wires share a single neutral, through using three conductor cable, the hot wires must be of opposite phases. If you are moving one wire of a pair, you must be sure to move it to a breaker of the same phase that it was originally. If you don't the current in the neutral can be doubled and overheat the wire.

BTW - are you allowed to move wires like that? I was under the impression that the hot lines in 3-conductor cable had to be in adjacent breakers, and the breakers had to be mechanically connected together so that they will both trip if either one trips. Does that only apply to split outlets that have both phases in the same outlet box?

I state what I need to state in such a fashion as to gently force the poster to get back with if the concept is understood, or ask more questions.

You are getting two things confused.

You are correct that if two circuits share a neutral, the two circuits need to be on opposite "phases", for the purpose of balancing the current in the neutral.

If both circuits carrying the same load, and the assumption is that both circuits can carry the max of that circuit rating, the current in the neutral will be zero.

If thou, for example, two 20 amp circuits on the same phase draw 20 amps each and use a shared neutral, the current in the neutral will be 40 amps, far too much than the #12 wire is allowed.

However, under most situations, these two "phases" do not end up exposed at the same device. This situation does not require a two pole breaker with common trip.

A common trip breaker is needed only if the two circuits from opposite "phases" are connected to one device, say a duplex receptacle. For example, you can have one circuit for a washer and another circuit for a gas dryer.

If the device is pulled out, there is 240 volts across the two hot terminals of the outlet. This is hazardous to the person working on the outlet, not being aware that there are two circuits, either coming in contact with 240 volts, or shutting one circuit off thinking the entire device is dead.

This requires a two pole switch or circuit breaker with common handle so that if one circuit is shut off to work on, both circuits at the device are dead.

Now, this has been a code for residential only, all other installations did not require this practice, until the 2005 editon of the code, where all installations must use a common handle disconnect for all circuits on one device.

Which really makes sense, and I always did even thou was not required.

Quote:

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Originally Posted by tkrussell

You do not add up the ratings of circuit breakers to match the rating of a panel, or any distribution equipment. The 200 amp load can be for one circuit or can be accumulated of several circuits. Install all the branch breakers you like in any combination, just be sure the total connected load does not exceed 200 amps.

Since the neutral from the generator must connect to the main system neutral in the main panel, the GFI breaker can have it's pigtail go back to the main neutral bar using the same size wire for the rating of the breaker.

Spliting the two wires on one breaker can be a problem. You will need to be absolutely sure the wire you move is on the same phase as the other one. If you don't, the current in the neutral can be doubled and overheat the wire. This can be difficult to understand and explain. Better you don't split this up unless you are sure of what you are doing.

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Thanks for your help That's all I needed to know, thanks again

I'd have to see it to understand it. I do know of someone that tried to backup their power with a generator and the transfer switch did not isolate the neutral.

The generator immediately triped on ground fault (because on a house, the neutral is grounded and on the generator, the neutral is isolated).

The statement, (because on a house, the neutral is grounded and on the generator, the neutral is isolated)., is not true, and is misleading.

There are two types of generator installations, Separately Derived Systems and Non-Separately Derived Systems. This is dictated strictly by the type of ATS ( Automatic Transfer Switch) that is ordered.

Typical, the most popular for general use is the Non-Separately Derived System ATS, and the neutral is NOT switched, and must connect to the Main Neutral of the electric service being supplied.

The Neutral is not isolated on a Separately Derived System ATS. These are not used for general purposes, such as backup power to building power, especially a home service. These are normally used in large commercial and industrial applications with special considerations.

Grounding and connection of neutral for a generator system is widely misunderstood, and frequently is done incorrectly.

Short answer is , if the transfer switch does not switch the neutral, then the neutral must be connected to the system neutral.